1. Field of the Invention
The present invention relates to unwoven tapes, in particular single-sided adhesive tapes, patches or stickers for holding medical devices, such as needles or sensors, BandAids or in particular dressings intended for the atraumatic contact of the healthy skin and of the wound.
2. Description of the Related Art
Usually, the adhesive tapes intended for the preparation of dressings and for the holding of medical devices are composed of a flat substrate, such as, for example, sheets of nonwoven, wovens, films or membranes coated on one side either with an acrylic adhesive polymer or with rubber-based formulations comprising resins, plasticizers or polymers having an instantly adhesive nature.
These compositions are generally based on polymers of high molecular weight and the adhesiveness on the skin depends on the composition and on the nature of the tackifying resins used.
These polymers having a high molecular weight confer, on the formulation, high viscosities generally of greater than several thousand mPa·s, which require a suitable process for coating the substrate with a few tens of or a few hundred g/m2, which constitutes the layer generally necessary in order to obtain sufficient adhesion to the substrate and to the skin.
In order to satisfactorily coat the substrate as explained above, the formulation is generally dissolved in a solvent, or is prepared as an aqueous emulsion, and this solution is subsequently coated by conventional coating processes, for example using a scraper or rollers, before evaporating the solvent through passing through a hot air oven, in order to obtain a dry layer of appropriate formulation.
In some cases, solvent-free hot-melt polymers can be used. In this case, the coating must be carried out during the phase of melting the polymer, before cooling and solidifying the polymer layer on the substrate.
Usually, the high viscosity of the compound in solution or in emulsion or in the molten state requires adjustment of the viscosity of the liquid form in order to regulate the coating of the surface of the substrate in contact with the skin.
Furthermore, from a functional viewpoint, these polymer compositions contribute to the appearance of polymer residues adhesively bonded to the skin during the removal of the adhesive. Thus, the use of polymers/compositions of this type, this very high adhesion and the low biocompatibility (irritability, sensitivity of the skin) of these ingredients cause traumatic adhesion of the tape to the skin, in particular to delicate skin, such as that of elderly people, children, premature babies or burn victims.
Very recently, there have been developed and have appeared on the market a few “light” adhesive tapes based on PSA (Pressure-Sensitive Adhesives) silicone polymers. These compositions are based on partially or completely crosslinked silicone rubber comprising silicone resins having a high tackifying power which provide the tape with significant contact adhesion on the skin.
However, in the same way, the high viscosity of these polymers requires dissolution in a solvent in order to adjust the rheology of the liquid paste in order to coat them on a flat substrate.
Generally, the polarity of the solvents used and the low viscosity of the solution are such that the fibers of the substrate are completely impregnated and the solution can pass through them in order to exude on the external face of the substrate, which then becomes instantly adhesive and unsuitable for winding of the tape over itself and for subsequent external use on a patient.
Furthermore, the nature of the solvents used results, during their use, in high risks to the health and safety of the manufacturing personnel and to the environment, and also in high costs.
In order to prevent the tackifying composition from passing through the tape towards its external face, nonwoven suppliers or tape manufacturers have carried out the laminating, on the internal face of the nonwoven, of a membrane or of a film of polymer generally based on polyurethane or on polyolefin, before coating said membrane with the tackifying composition.
However, this operation represents a significant cost and high risks for the achievement of strong adhesion of the tackifying composition to this film.
This risk of low adhesion in its turn constitutes a high risk of delamination of the adhesive layer and of the substrate during the removal of the tape from the skin of the patient, with the disadvantages of residues and of trauma on the skin which are described above.
Thus, the solutions of the prior art are not entirely satisfactory.
One aim of the present invention is thus to solve the abovementioned problems using a solution which is simple to manufacture, relatively inexpensive, easy to use and optimized in terms of effectiveness.